Film forming composition

ABSTRACT

A film forming composition including a film forming substance having amphiphilic molecules and being dispersed in a gel-like carrier having a non-liquid state below about 20° C. The carrier stabilizes the film forming substance, and inhibits diffusion of moisture and oxygen into the composition. This minimizes deterioration of the film forming substance, and also minimizes undesirable formation of agglomerations of such substance. When the composition is applied to a surface, an ultra thin substantially continuous film of substantially uniform thickness forms spontaneously and attaches to the surface. The excess composition is then washed away.

BACKGROUND OF THE INVENTION

This application relates to the art of coating compositions and tomethods for providing surfaces with coatings. The invention isparticularly applicable to ultra thin films formed by amphiphilicmolecules, and will be described with specific reference thereto.However, it will be appreciated that certain features of the inventionhave broader aspects, and may be used with other types of film formingsubstances and coating compositions.

Compositions having ingredients that are capable of forming thin filmson substrates are discussed in an article entitled OleophobicMonolayers, by W. C. Bigelow et al., J. Colloid Sci. I, pages 513-538(1946); in an article entitled Wettability and Conformation of ReactivePolysiloxanes, by Lieng-Huang Lee, Journal of Colloid and InterfaceScience, Vol. 27, No. 4, August 1968, pages 751-760; in an articleentitled Electrical Conduction Through Adsorbed Monolayers, by E. E.Polymeropoulos et al., J. Chem. phys. 69(5), Sept. 1, 1978, pages1836-1847; and in U.S. Pat. No. 4,539,061 issued Sept. 3, 1985, to JacobSagiv, for a Process for the Production of Built-Up Films by theStepwise Adsorption of Individual Monolayers The disclosures of whichare hereby incorporated herein by reference. These compositions use thinsolvents in which a film forming substance is soluble. In general, thesolvents are toxic and environmentally unsafe. Highly liquidcompositions also lose their usefulness very rapidly when exposed toairborne moisture and/or oxygen. Highly reactive materials tend to formmolecular agglomerations and precipitate out of solution.

It would be desirable to have a film forming composition that is notnoxious or hazardous to persons or the environment, and that wouldprovide optimum protection and stability for a film forming substance inthe composition. At the same time, it would be desirable to provide sucha composition that is easily applied to substrate surfaces to form asubstantially continuous ultra thin film of substantially uniformthickness thereon.

SUMMARY OF THE INVENTION

Film forming substances used in the compositions of the presentapplication are capable of forming films and attaching to substrates byreactions and forces of the type discussed in the aforementionedarticles by Bigelow et al., L. H. Lee, E. E. Polymeropoulos et al., andJ. Sagiv. The film is chemically bound to a surface on which it forms.

A film forming substance capable of forming a substantially continuousultra thin film of substantially uniform thickness is dispersed in acarrier having a non-liquid state at temperatures below about 20° C.

Unlike prior arrangements requiring use of a solvent in which a filmforming substance is soluble, the present application makes it possibleto use a carrier in which the film forming substance is either solubleor insoluble. When using a carrier in which the film forming substanceis insoluble, the film forming substance is uniformly dispersedthroughout the carrier to provide a substantially homogeneous mixture.

The carrier is preferably non-aqueous and is preferably insoluble inwater. However, aqueous carriers may be possible for certainapplications. Also, the carrier preferably has a substantially neutralpH, although acidic or basic carriers may be used for certain purposes.

The carrier is preferably a gel or gel-like material which inhibitsdiffusion of moisture and/or oxygen into the composition to therebystabilize the film forming substance and minimize deterioration of same.

In the present application, amphiphilic molecules form an ultra thinsubstantially continuous film of substantially uniform thickness, andattach to a substrate surface from a composition having a gel orgel-like state, instead of a liquid state, at temperatures below about20° C.

In the most preferred arrangement of the present application, the filmforming substance consists essentially of amphiphilic molecules. Thatis, the film formed on a surface using the composition of the presentapplication is formed solely from amphiphilic molecules in thecomposition.

Film formed in accordance with the present application is characterizedby its substantially uniform thickness not greater than about 0.5micron.

Compositions of the present application have a preferable consistencyrange at 25° C. of about 35-400 by the cone penetration test. However,lower consistency can be used, and the consistency is preferably notgreater than about 400 at 25° C.

The preferred melting point is higher than about 30° C., and mostpreferably higher than about 50° C. A preferred melting point range isabout 30°-80° C., although higher melting points can be used bypreheating the composition and/or the substrate to which it is applied.Lower melting point compositions are preferred for ease of application,and minimize or eliminate the need to preheat the composition and/orsubstrate.

Compositions of the present application can employ up to about 0.5% byweight of a catalyst, such as zinc chloride, aluminum chloride ormineral acids, to enhance film formation.

Compositions of the present application can employ up to about 0.5% byweight of a quencher, such as one or more of amines, aluminum powder andzinc powder, for reaction with noxious fumes. For example, if thecomposition uses materials that react to form acid fumes, the quencherwill neutralize the acid fumes by forming a salt.

Compositions of the present application are particularly useful forproviding ultra thin films on cookware, and especially glass cookware,on glass laboratory ware and on eyewear lenses.

Compositions of the present application can change the surface energy ofsurfaces to which they are applied.

Preferred films formed in accordance with the present application aresubstantially invisible unless a dye is added to the composition orincorporated in the amphiphile.

The composition of the present application is applied to a substratesurface, and a substantially continuous ultra thin film of substantiallyuniform thickness is allowed to form from the amphiphilic molecules inthe film forming substance. The molecules also attach themselves to thesubstrate surface by various forces and bonds as discussed in theaforementioned articles, and are primarily chemically bound to thesurface. Subsequently, the excess material is washed away, such as withsoap and water. A substantially continuous ultra thin film ofsubstantially uniform thickness remains on the substrate surface, andprovides excellent abrasion and stain resistance. The propertiesimparted to the substrate surface by the film can be varied by selectingdifferent film forming substances.

The method of the present application for providing a substantiallycontinuous ultra thin film of substantially uniform thickness to asubstrate surface is essentially carried out in three steps. First, ahomogeneous coating composition is made by dispersing a film formingsubstance in a carrier having a viscosity such that diffusion ofmoisture and/or oxygen into the composition is inhibited. Thisstabilizes the film forming substance and minimizes deterioration ofsame. Small quantities of one or both of a catalyst and quencher may beincluded in the composition. Second, the composition is applied to asubstrate surface. Third, the amphiphilic molecules in the film formingsubstance are allowed to form a substantially continuous ultra thin filmof substantially uniform thickness that attaches to the substratesurface. Film forming substances containing polymerizable moieties arepolymerized by heating, photochemical reaction and/or use of a catalyst.Excess coating material is then washed away.

It is a principal object of the present invention to provide an improvedcoating composition and method for providing ultra thin films onsubstrate surfaces.

It is another object of the invention to provide a coating compositionhaving a substantially neutral carrier that is environmentally safe andnon-toxic to persons.

It is an additional object of the invention to provide an improvedcoating composition and method for forming ultra thin films in a mannerthat does not release hazardous materials to the environment, or createa noxious or hazardous environment for workers.

It is a further object of the invention to provide a coating compositioncontaining a film forming substance that is very stable and resistant todeterioration, while being very reactive for film formation.

It is another object of the invention to provide a coating compositionhaving an extremely low moisture content and a very low affinity formoisture.

It is another object of the invention to provide a coating compositionthat inhibits diffusion of moisture into the composition to therebyminimize deterioration of a film forming substance within thecomposition.

It is also an object of the invention to provide improved substratesurfaces, such as on cookware, laboratory ware and eyewear lenses.

It is another object of the invention to provide a commercially costeffective composition and method for modifying surface properties ofsubstrates by forming substantially continuous ultra thin films ofsubstantially uniform thickness thereon.

DESCRIPTION OF PREFERRED EMBODIMENTS

As used in this application, a film forming substance is one containingamphiphilic molecules that are capable of forming a substantiallycontinuous ultra thin film of substantially uniform thickness on asubstrate surface. In this application, a substantially continuous filmis one that is substantially unbroken except for the presence ofrelatively minor defects or imperfections such as pin holes.

An amphiphile contains a polar region and a non-polar or apolar region.Amphiphiles that can be used to form film in accordance with the presentapplication include, but are not necessarily limited to, the following:

The polar segment of the amphiphile can be a carboxylic acid or itssalts, alcohols, thiols, amides, primary, secondary, tertiary amines,cyanides, nitrates, phosphates, silane derivatives, sulfonates and thelike.

The non-polar or apolar component typically consists mainly of alkanesor fluorinated alkanes. These apolar regions may include diacetylene,vinyl-unsaturated, or fused linear or branched aromatic moieties. Inaddition the apolar region may contain organic dyes with or withoutmetal, such as pthalocyanines, porphyrins and phenol blues.

In one preferred arrangement, the film forming substance consistsessentially of RmSiXn where the non-polar R is an alkyl or fluorinatedalkyl group of about 10-30, and most preferably about 14-30, carbonatoms long. The film forming substance, and particularly the alkyl orfluorinated alkyl group, may include one or more of polymerizablemoieties, dyes or dipoles. In the above formula, X is selected from thegroup consisting essentially of halogens, hydroxy and alkoxy. In theformula, m is 0-3, n is 1-4, and m plus n equal 4. In still anotherpreferred arrangement, R may be a substituted silane or siloxane.

The film forming substance is thoroughly mixed and uniformly dispersedin a carrier to provide a substantially homogeneous composition. Thecarrier is preferably one that has a non-liquid state at temperaturesbelow about 20° C. Most preferably, the carrier is one having asubstantially neutral pH, although other types of carriers can be usedfor certain purposes. Most preferably, the carrier is one that meetsFood and Drug Administration Regulations 21 CFR 172.880 and 178.3700 fordirect and indirect use in food for human consumption.

The carrier used in the composition of the present application ispreferably a gel or gel-like material at temperatures below about 20° C.Various grades of petrolatum can be used for the carrier. Thesepetrolatums are of the type used as carriers, emollients, lubricants,base ingredients, binders, protective coatings, plasticizers,waterproofing, release agents, and softeners. The carrier may also be amineral jelly compounded from white mineral oils, petrolatums andparaffin waxes. The carrier may also be a hydrogenated or partiallyhydrogenated vegetable or animal oil. Various mixtures of theaforementioned carriers are also possible.

Most preferably, the carrier is one that is not soluble in water.However, carriers that are soluble in water can be used for certainpurposes. The carrier may be one in which the film forming substance isinsoluble. Other carriers that may be possible for certain purposesinclude silicone jelly. Water based gels may also be used when the filmforming substance does not react with water. The carrier is preferablyone that has an extremely low moisture content and most preferably isone that has been rendered anhydrous.

The highly viscous carrier stabilizes the film forming substance bymaintaining same randomly dispersed throughout the carrier. The carrieralso inhibits absorption of airborne moisture and/or oxygen into thecomposition.

A small quantity of a catalyst may be uniformly mixed in the compositionto enhance film formation. For example, up to about 0.5% by weight ofone or more of zinc chloride or mineral acids may be added to thecomposition. A small quantity of a quencher may also be added to thecomposition for neutralizing acid fumes formed during film formation.For example, up to about 0.5% by weight of one or more of an amine,aluminum powder or zinc powder may be added to the composition as aquencher that will neutralize acid fumes by forming a salt. When morethan one quencher is used, the total amount of quencher material is notmore than about 0.5% by weight of the entire composition, and the samerelationship is used for the catalyst.

The composition and carrier of the present application have a preferredconsistency or firmness as determined by a cone penetration test.Examples of consistency will be given as determined by ASTM designationD937-87 approved Oct. 30, 1987, and published in December 1987, thedisclosure of which is hereby incorporated herein by reference. Thecarrier and composition of the present application preferably have aconsistency at 25° C. that is in the range of about 35-400, although alower consistency can be used when the substrate and/or composition isheated before application of same to a surface.

In the cone penetration test for consistency, higher numbers mean thatthe material is softer because the cone penetrates further. Thus, amaterial having a consistency of 35 is much firmer and resistant topenetration than a material having a consistency of 400. The consistencyof the carrier and composition is preferably less than about 400. A morepreferable range is about 150-300.

The preferred melting point of the composition is higher than about 30°C., and most preferably higher than about 50° C. A preferred meltingpoint range is about 30°-80° C., although higher melting points can beused by heating the composition and/or substrate. Lower melting pointsare preferable for ease of application of the composition to a surface,while eliminating or minimizing the need to preheat the compositionand/or substrate. The melting point may be determined in accordance withASTM designation D127.

The composition of the present application can be applied to substratesurfaces in any suitable manner, such as by wiping, brushing, rolling,spraying or the use of a doctor blade. The composition can also befoamed as it is applied to a substrate surface or as an article to becoated with film is passed through the foam. The composition can also bevaporized, and articles to be coated with film are passed through thevapor.

To form a substantially continuous ultra thin film of substantiallyuniform thickness on a substrate surface, the surface is completelycovered with the composition. The composition is allowed to remain onthe surface for a sufficient period of time to allow the film to formand attach to the surface. The amount of time required for filmformation and bonding to the surface depends upon the type of substrate,the consistency of the composition, the temperature and the particularfilm forming substance being used.

Where the film forming substance contains a polymerizable group, thefilm may be cured by either heating or exposure to a light source,preferably an ultraviolet light source. Polymerization can be initiatedat anywhere from 20° C. to 150° C. Heat may be applied by blowing hotair on the surface or by passing the articles through an oven.Polymerization may be effected during a time period up to about 30minutes. When X in RmSiXn is a halogen, polymerization can be completedin less than one minute and, when a non-halogen, can be substantiallycompleted in up to about 30 minutes

Once the film has formed and is attached to the substrate surface, theexcess composition is washed away. The excess composition may be removedwith a suitable solution, such as soap and water, and then rinsed. Asuitable solvent such as mineral oil may also be used to provide aninitial rinse for washing away the excess composition. The substratesurface is left with a film having excellent abrasion and stainresistance. The film is substantially invisible unless a dye has beenadded to the composition or incorporated in the amphiphile.

The composition and method of the present application are particularlyadvantageous for providing a film of the type described on non-poroussubstrates, such as glass, plastics, ceramics, porcelain, fiberglass andmetals. Film applied in accordance with the present application isrelatively permanent in nature, and resists all common householdsolvents and chemicals, along with food products and cosmetics. The filmis hydrophobic, and also has excellent water beading and anti-stickproperties. The film is useful for anti-reflective optics, corrosionprotection, friction reduction, print priming, moisture barriers,scratch resistance and security marking. The film is particularlyadvantageous when applied to cookware, and particularly glass or ceramiccookware, to laboratory ware and to eyewear lenses used in eyeglasses.

Film applied with the composition of the present application is usefulon any pots, pans, dishes or utensils used for preparing, cooking andserving food. The film is particularly advantageous on such items thatare made of glass and are used for cooking, because dried food does notstick to the film.

The film is also advantageous on glass laboratory ware including, butnot limited to, laboratory flasks, beakers, test tubes and dishes.

The film is particularly advantageous for use on plastic eyewear lenses,such as aliphatic polycarbonate, used in eyeglasses. An anti-reflectivecoating and/or scratch resistant coating may be applied to the lensesbefore the film of the present application is formed thereon. The lensesmay have a thin anti-reflective coating of sputtered metal thereon andthe film is applied over the anti-reflective coating. The lenses may behard coated for scratch resistance, such as with a polysiloxane, and thefilm of the present application is applied over the scratch resistantcoating.

In the arrangement of the present application, the sole material thatforms the film in-situ on a substrate surface consists essentially ofamphiphilic molecules. That is, the sole material in the finished filmconsists essentially of amphiphilic molecules from the film formingsubstance. The film is characterized by its highly uniform thickness ofnot more than about 0.5 microns.

Although the invention has been described with reference to certainpreferred embodiments, it is obvious that equivalent alterations andmodifications will occur to others skilled in the art upon the readingand understanding of this specification. The present invention includesall such equivalent alterations and modifications, and is limited onlyby the scope of the claims.

We claim:
 1. A composition consisting essentially of a film formingsubstance and a carrier for said film forming substance, said carrierconsisting essentially of a material having a non-liquid gel state attemperatures below about 20° C. and a melting point not greater thanabout 80° C., said film forming substance being dispersed in saidcarrier and consisting essentially of polymerizable amphiphilicmolecules that automatically separate from said composition andself-assemble into a substantially continuous ultra thin film ofsubstantially uniform thickness not greater than about 0.5 micron on asurface to which said composition is applied, such film being chemicallyattached to surfaces on which it forms from said composition, theremainder of the composition being readily removable from a surface towhich it is applied to leave only the self-assembled film on suchsurface, said composition having a consistency for allowing readyapplication thereof to surfaces in continuous covering relationshipthereto at temperatures above and below 20° C. wherein the filmsubstance consists essentially of RmSiXn where R is an apolar alkyl orfluorinated alkyl group of about 10-30 carbon atoms, where m plus nequals four, and where X is selected from the group consisting ofhalogens, hydroxy and alkoxy groups.
 2. The composition of claim 1wherein said carrier has a substantially neutral pH.
 3. The compositionof claim 1 wherein said film forming substance is insoluble in saidcarrier.
 4. The composition of claim 1 wherein said carrier isimmiscible in water.
 5. The composition of claim 1 wherein said carrierincludes petrolatum.
 6. The composition of claim 1 wherein asubstantially major portion of said carrier, by percent weight of saidcomposition, comprises petrolatum.
 7. The composition of claim 1 whereinsaid film forming substance comprises about 0.1-20% by weight of saidcomposition.
 8. The composition of claim 1 wherein said film formingsubstance comprises about 1-5% by weight of said composition.
 9. Thecomposition of claim 1 wherein R includes one or more of polymerizablemoities, dyes or dipoles.
 10. The composition of claim 1 wherein saidfilm forming substance is polymerizable by at least one of heat orlight.
 11. The composition of claim 1 wherein heat polymerization ofsaid film forming substance is at least started at a temperature ofabout 20°-150° C.
 12. The composition of claim 11 wherein said filmforming substance is at least partly polymerized at said temperature ofabout 20°-150° C. when maintained at such temperature for a time periodup to about 30 minutes.
 13. The composition of claim 1 wherein said filmforming substance is photopolymerizable by ultraviolet radiation. 14.The composition of claim 1 including a catalyst for promoting filmformation by said film forming substance.
 15. The composition of claim 1including a quencher for neutralizing undesirable reaction by-productsresulting from film formation by said film forming substance.
 16. Thecomposition of claim 1 wherein said composition has a consistency asmeasured by an ASTM cone penetration test of between about 35-400 at 25°C.
 17. The composition of claim 1 wherein said composition has aconsistency as measured by an ASTM cone penetration test of betweenabout 150-300 at 25° C.
 18. The composition of claim 1 wherein saidcomposition has a consistency not greater than about 400 at 25° C. asmeasured by an ASTM cone penetration test.
 19. The composition of claim1 wherein said carrier substantially meets Food and Drug AdministrationRegulations 21 CFR 172.880 and 178.3700 for direct and indirect use infood for human consumption.
 20. A coating composition for providing atransparent abrasion and stain resistant film on substrate surfacescomprising;a substantially homogeneous mixture of a carrier whoseprincipal ingredient is petrolatum and a film forming substance ofpolymerizable amphiphilic molecules having polar groups and beingcapable of spontaneous thin film formation in-situ on a substratesurface when said composition is applied to such surface, said carrierproviding protection for said film forming substance and stabilizingsame by maintaining said molecules in a substantially disoriented statewithin said carrier until said composition is applied on a substratesurface whereupon said molecules form in-situ on said surface into asubstantially continuous ultra thin film of substantially uniformthickness not greater than about 0.5 micron with said polar groupschemically attached to such surface, said composition beingcharacterized by the absence of solid particulate materials wherein thefilm substance consists essentially of RmSiXn where R is an apolar alkylor fluorinated alkyl group of about 10-30 carbon atom, where m plus nequals four, and where X is selected from the group consisting ofhalogens, hydroxy and alkoxy groups.
 21. The composition of claim 20wherein said non-polar segment of an alkyl or fluorinated alkyl groupincludes one or more of polymerizable moieties, dyes and dipoles.
 22. Asubstantially anhydrous composition comprising a film forming substanceand a carrier for said film forming substance, said film formingsubstance comprising polymerizable amphiphilic molecules capable ofbonding self-assembly into a substantially continuous ultra thin film ofsubstantially uniform thickness not greater than about 0.5 micron on asurface to which they are applied, said carrier comprising asubstantially anhydrous material having a gel state at temperaturesbelow about 20° C., a melting point not greater than about 80° C., and aconsistency not greater than about 400 at 25° C., as measured by an ASTMcone penetration test, said film forming substance being dispersed insaid carrier, said polymerizable amphiphilic molecules in said filmforming substance being automatically separable from said carrier byattractive forces between said molecules and a surface to which saidcomposition is applied for bonding self-assembly on such surface intosaid ultra thin film, said polymerizable amphiphilic moleculescomprising substantially the only ingredient of said composition thatforms an adherent permanent coating on a surface to which saidcomposition is applied, said carrier forming no part of an adherentpermanent coating on a surface to which said composition is applied andsaid carrier being readily removable form a surface to which saidcomposition is applied to leave only the ultra thin film formed by saidpolymerizable amphiphilic molecules wherein the film substance consistsessentially of RmSiXn where R is an apolar alkyl or fluorinated alkylgroup of about 10-30 carbon atoms, where m plus n equals four, and whereX is selected from the group consisting of halogens, hydroxy and alkoxygroups.
 23. The composition of claim 22 wherein substantially all ofsaid composition, other than said film forming substance, substantiallymeets United States Food and Drug Administration Regulations 21 CFR172.880 and 178.3700 for direct and indirect use in food for humanconsumption.
 24. The composition of claim 22 wherein said carrier has aconsistency not less than about 35 at 25° C. as measured by an ASTM conepenetration test.
 25. The composition of claim 22 wherein saidcomposition has a consistency between about 150-300 at 25° C. asmeasured by an ASTM cone penetration test.